长江干支流输沙量减少趋势及其影响因素浅析

通过对长江干支流各主要水文控制站的多年径流量、输沙量、含沙量、中值粒径等水沙基本特征值的统计分析，表明在过去的近50年时间内，长江干支流的年径流量中心趋势不存在具有显著统计意义的变化，而输沙量、含沙量、中值粒径值均有明显的下降态势。以水库建设和水土保持为主的人类活动是长江干支流泥沙输移量减少趋势的重要影响因素，在20世纪90年代以前长江输沙量的减少主要是水库建设的影响，之后随着“长治”工程的展开则兼具了水库建设和水土保持的影响，未来水土保持工作对长江保水减沙的长期效益将更为显著。

A BRIEF ANALYSIS ON THE REDUCTION TREND AND INFLUENTIAL FACTORS OF SEDIMENT DISCHARGE IN THE YANGTZE RIVER AND ITS TRIBUTARIES

According to the statistic analysis of long-term annual runoff, sediment discharge, sediment concentration and median diameter of suspended sediment obtained from the main hydrometric control stations of Yangtze River and its tributaries, the major trend in the annual runoff of the Yangtze River and its tributaries had no obvious changes, while their sediment discharge, and median diameter of suspended sediment had a decreasing trend. Human activities such as reservoir construction and water-and-soil conservation projects are the key factors influencing the reduction of sediment discharge of Yangtze River and its tributaries. Before 1990s, the key factor that influenced the reduction of sediment discharge in the river and its tributaries was reservoir construction. After the launch of water-and-soil conservation project in the Yangtze basin, both reservoir construction and water-and-soil conservation became the key factors. The waterand-soil conservation will be remarkable influential to the long-term benefit of Yangtze Rivers water protection and sediment reduction in the future.